What Is Foundation
Foundation is an important part of the structure which transfers the
load of the structure to the foundation soil. The foundation distributes
the load over a large area. So that pressure on the soil does not exceed its allowable bearing capacity and restricts the settlement of the structure within the permissible limits.
The different type of footing used in building construction are classified as Shallow and Deep Foundation
Type Of Foundations Used In Construction
1. Shallow Foundation
- Isolated Footing
- Combined Footing
- Strip Foundation
- Raft or Mat foundation
2. Deep Foundation
- Pile Foundation
- drilled shaft or caisson
Type Of Shallow Foundation
1. Isolated Footing
Isolated footing or Individual footing is the most common type of footing used in building construction. this footing provided under each individual column. usually the section of this footing square or rectangular.
Isolated footings are provided where the soil bearing capacity is
generally high and it comprises of a thick slab which may be flat or
stepped or sloped. This type of footings are most economical when
compared with the other kind of footings.
2. Combined Footing
When two or more column are supported by a footing called combined footing. This footing may be trapezoidal or rectangular in section.
Combined footing are provided when individual footing is overlap or space between two footing is too close.
3. Strip Foundation
This type of footing is constructed for Load bearing walls. It is a continuous strip of concrete that serves to spread the weight of a load-bearing wall across an area of soil. This footing is also called wall footing.
4. Raft Or Mat Foundation
A raft or Mat foundation is a solid reinforced concrete slab covering entire
area beneath the structure and supporting all the columns.This foundation cover the entire area under the structure.
It is provided in a places like seashore area, coastal area area where
the water table is very high and soil bearing capacity is very weak. or when a heavy structure is constructed on a soft made-up ground.
Type Of Deep Foundation
1. Pile Foundation
Pile foundation is a type of deep foundation which is used to transfer
heavy loads from the structure to a hard rock strata much deep below the
ground level
Pile foundations are generally used for soils where soil conditions near
the ground surface is not suitable for heavy loads. The depth of hard
rock strata may be 5m to 50m (15 feet to 150 feet) deep from the ground
surface
2. Drilled Shaft or Caisson
Drilled shafts, also called as caissons, is a type of deep foundation
and has an action similar to pile foundations discussed above, but are
high capacity cast-in-situ foundations. It resists loads from structure
through shaft resistance, toe resistance and/or combination of both of
these.
Drilled shafts can transfer column loads larger than pile foundations.
It is used where the depth of hard strata below ground level is located
within 10m to 100m (25 feet to 300 feet)
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